text: import FirstLetterIndex from '../../lib/HamCallsignDB/callsignindexone.json'
  import SecondLetterIndex from '../../lib/HamCallsignDB/callsignindextwo.json'
  import ThirdLetterIndex from '../../lib/HamCallsignDB/callsignindexthree.json'
  import FourthLetterIndex from '../../lib/HamCallsignDB/callsignindexfour.json'
  
  const getAmateurRadioInfoByCallsign = (callsign) => {
      if(typeof callsign !== 'string'){
          console.error('[callsign.js]: Callsign must be string')
          return;
      }
      callsign = callsign.toUpperCase()
      let result1 = FirstLetterIndex.find((x) => {
          return x.prefix === callsign.substring(0, 1)
      })
      let result2 = SecondLetterIndex.find((x) => {
          return x.prefix === callsign.substring(0, 2)
      })
      let result3 = ThirdLetterIndex.find((x) => {
          return x.prefix === callsign.substring(0, 3)
      })
      let result4 = FourthLetterIndex.find((x) => {
          return x.prefix === callsign.substring(0, 4)
      })
      let result
      if(result4===undefined){
          if(result3===undefined){
              if(result2===undefined){
                  if(result1===undefined){
                      result = undefined
                  }else{
                      result = result1
                  }
              }else{
                  result = result2
              }
          }else{
              result = result3    
          }
      }else{
          result = result4  
      }
      return result
  }   
  export default getAmateurRadioInfoByCallsign